"Tubes" video game

Tubes started out as an Atari 7800 game, but got bogged down partly because
the 7800 video chip steals too many bus cycles if you display too much data
on the screen. Also, I've never been a fan of 6502 code.

The current status is that all Atari 7800 version features have been
completely ported over to the Sega Genesis, and a few extra features
(like a title screen) added.